Work on SMS features

htdocs/admin/sms.php

htdocs/comm/propal.php

htdocs/commande/fiche.php

htdocs/compta/facture.php

htdocs/core/class/html.formmail.class.php

htdocs/core/class/html.formsms.class.php

htdocs/fourn/commande/fiche.php

htdocs/fourn/facture/fiche.php

htdocs/langs/en_US/admin.lang

htdocs/langs/fr_FR/admin.lang

htdocs/langs/fr_FR/sms.lang

htdocs/lib/functions.lib.php

htdocs/societe/class/societe.class.php